In the manufacture of a dynamoelectric machine rotor, a large number of core material laminae are assembled onto the rotor shaft. A specified orientation of the laminae is required to properly define the rotor poles and conductor./winding slots, and such orientation is commonly achieved by keying the laminae to the shaft. That is, a key or ridge is formed on the shaft along the length of the lamination stack, and a complementary keyway is formed on each lamination.
Typical examples of conventional practice are shown in FIGS. 1a14 1b. In FIG. 1a, a single key 10 and keyway 12 is employed. A peculiar disadvantage of this approach is that the keyway 12 on the rotor shaft 14 does not prevent reversing of the laminae 16. As a result, the laminae 16 may not stack properly, and there may be some misalignment of the openings 18 of the assembly. Moreover, dimensional variations in the laminae 16 stack up or accumulate since the angular orientation of each lamination is identical. This results in rotor imbalance and may cause difficulties in winding insertion or casting.
In the rotor of FIG. 1b, a second key 20 and keyway 22 are employed at an asymmetric orientation to prevent laminae reversal. However, the cumulative lamination stack-up, and the attendant manufacturing difficulties, still occur.
In other known designs, multiple keys and keyways are formed symmetrically about the rotor shaft to distribute the dimensional variation by indexing successive laminations. See, for example, Mayer et al. U.S. Pat. No. 4,585,96